Glial responses during evoked behaviors in the leech

Glial cells can respond with membrane potential changes during electrically stimulated neuronal activity (Kuffler, Proc R Soc Lend B 168:1-21, 1967; O rkand, Oxford University Press, 1995). Their role in contributing to, or co ntrolling, neural circuits underlying behaviors, however, is completely unk nown. We have used semi-intact preparations of the leech Hirudo medicinalis , where behaviors can be elicited and monitored (Kristan et al., J Neurobio l 27:380-389, 1995), to record membrane responses of identified glial cells during whole-body shortening and during fictive swimming. Giant glial cell s are located in the neuropil of segmental ganglia, where neuronal axons an d dendrites establish numerous synaptic contacts (Coggeshall and Fawcett, J Neurophysiol 27:229-289, 1964). We report here that these glial cells hype rpolarize when the whole-body-shortening response is evoked but not during fictive swimming. To our knowledge, this is the first report that associate s a specific behavior with glial cell responses. GLIA 26:186-189, 1999. (C) 1999 Wiley-Liss, Inc.